082
FXUS02 KWBC 011900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT THU AUG 1 2024
VALID 12Z SUN AUG 04 2024 - 12Z THU AUG 08 2024
...HAZARDOUS HEAT PERSISTS ACROSS THE SOUTHWEST AS HEAT
INTENSIFIES OVER THE SOUTH-CENTRAL U.S. NEXT WEEK...
...WATCHING TROPICAL THREATS FROM FLORIDA TO THE SOUTHEAST U.S.
COAST NEXT WEEK...
..OVERVIEW
UPPER RIDGING OVER THE WESTERN U.S. THIS WEEKEND WILL BE UP AGAINST
UPPER TROUGHING DIGGING DOWN CENTRAL CANADA TOWARD THE NORTHERN
PLAINS, CAUSING THE RIDGE TO GET SUPPRESSED WITH TIME AND EXTEND
EAST TOWARD THE SOUTH-CENTRAL U.S. NEXT WEEK. THIS PATTERN WILL
SUSTAIN HEAT ACROSS THE SOUTHWEST WHILE BRINGING A HEATWAVE INTO
THE CENTRAL PLAINS TOGETHER WITH ONGOING HEAT AND HUMID ACROSS THE
SOUTH. NORTHERN STREAM FLOW AND ENERGY DIGGING TO THE LEE OF THE
UPPER RIDGE WILL REINFORCE TROUGHING OVER THE UPPER MIDWEST TO THE
EAST THAT LASTS THROUGH THE MIDDLE OF NEXT WEEK. THE NATIONAL
HURRICANE CENTER IS ALSO MONITORING THE POTENTIAL FOR TROPICAL
DEVELOPMENT THAT COULD AFFECT THE EASTERN GULF COAST AND THEN THE
SOUTHEAST U.S. COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE CONTINUES TO SHOW OVERALL GOOD AGREEMENT ON THE
LARGE SCALE PATTERN EVOLUTION ACROSS MAINLAND U.S. THROUGH NEXT
WEEK. HOWEVER, THERE REMAINS NOTICEABLE UNCERTAINTY IN THE TIMING
AND AMPLITUDE OF ENERGIES THROUGH THE NORTHERN TIER TO CARVE OUT A
MIDWEST/EASTERN U.S. MEAN UPPER TROUGH, ESPECIALLY LATER IN THE
PERIOD. ALSO QUESTION ON THE EXTENT AND STRENGTH OF THE UPPER RIDGE
FROM THE SOUTHWEST INTO THE CENTRAL PLAINS/SOUTHEAST.
MODELS AND ENSEMBLES CONTINUE TO FAVOR POSSIBLE TROPICAL
DEVELOPMENT NEAR/SOUTH OF FLORIDA THIS WEEKEND BUT WITH A WIDE
VARIETY OF SOLUTIONS TO THE TRACK OF THE TROPICAL SYSTEM. FOLLOWING
AN OVERWHELMING WESTWARD SHIFT IN THE GUIDANCE FROM LAST NIGHT,
ALL MODELS HAVE SETTLED WITH TROPICAL CYCLONE DEVELOPMENT OVER THE
EASTERN GULF OF MEXICO THIS WEEKEND AS THE ECMWF ABANDONS ITS
LONG-HELD IDEA OF TROPICAL CYCLONE DEVELOPMENT EAST OF FLORIDA.
THEREAFTER, THE 00Z AND 06Z GFS SHOWED THE POSSIBILITY OF TURNING
THE CYCLONE BACK WEST TOWARD THE SOUTHEAST U.S. HOWEVER, THE 12Z
GUIDANCE INCLUDING THE ECMWF, UKMET, ICON, AND 06Z EC-AI MODELS
NOW GENERALLY SUPPORT AN EAST-NORTHEASTERLY TRACK NEAR/OFF THE
COAST OF THE SOUTHEAST U.S., WHICH IS THE TRACK PROPOSED BY THE
NATIONAL HURRICANE CENTER THROUGH DAY 7. THE CMC OFFERS AN
ALTERNATIVE SCENARIO BY RECURVING THE CYCLONE AND TURNING IT
EXTRATROPICAL ACROSS THE SOUTHEAST U.S., WHICH IS CONSIDERED TO BE
AN OUTLIER AT THIS POINT. IN ANY CASE, THIS SYSTEM WILL NEED TO BE
WATCHED FOR POSSIBLE HEAVY RAINFALL IMPACTS TO PARTS OF THE GULF
COAST/FLORIDA AND THE SOUTHEAST.
THE WPC MEDIUM RANGE FORECAST SUITE USED A BLEND OF THE
OPERATIONAL MODELS AND THEIR ENSEMBLE MEANS FOR THE FIRST HALF OF
THE PERIOD, BUT EXCLUDING THE CMC AND WESTWARD-MOVING GFS SOLUTIONS
FOR THE TROPICAL SYSTEM WHILE LEANING MORE TOWARDS THE ENSEMBLE
MEANS DAYS 6 AND 7 TO ACCOUNT FOR NORTHERN STREAM UNCERTAINTIES.
..WEATHER/HAZARDS HIGHLIGHTS
THE MAIN FOCUS FOR HEAVY RAINFALL THREATS DURING THE PERIOD WILL
LIKELY BE ASSOCIATED WITH WHATEVER BECOMES OF A TROPICAL
DISTURBANCE LIKELY TO AFFECT PARTS OF FLORIDA AND THE SOUTHEAST.
GUIDANCE THIS CYCLE SHOWED A DRASTIC SHIFT TOWARDS HEAVY RAINFALL
POTENTIAL FOR MUCH OF THE NORTHERN TO CENTRAL PARTS OF THE STATE.
THE DAYS 4 AND 5 EXCESSIVE RAINFALL OUTLOOKS COVERING SUNDAY-MONDAY
SHOW SLIGHT RISK UPGRADES ACROSS THIS REGION, WITH A BROADER
MARGINAL COVERING MUCH OF THE STATE TO ACCOUNT FOR THE LINGERING
UNCERTAINTY. IT IS LIKELY THESE AREAS WILL NEED TO BE MODIFIED AS
WE GET CLOSER IN TIME, BUT FOR NOW, THIS SEEMED THE MOST PLAUSIBLE
SOLUTION COVERING THE BETTER MODEL TRACK CONSENSUS. HEAVY RAINFALL
ACROSS FLORIDA MAY LINGER INTO NEXT WEEK WITH POSSIBLE EXTENSION
INTO PARTS OF THE SOUTHEAST DEPENDENT ON TRACK OF THIS SYSTEM.
ELSEWHERE, A FRONT EXITING THE NORTHEAST ON SUNDAY MAY BRING A
PERIOD OF LOCALLY HEAVY RAINFALL, WHICH CONTINUES TO BE COVERED IN
THE DAY 4 ERO. TO THE WEST, MODELS SHOW A POTENTIAL MESOSCALE
SYSTEM RIDING THE TOP OF THE RIDGE INTO THE UPPER MIDWEST EARLY
NEXT WEEK. A MARGINAL RISK ON THE DAY 4 ERO STRETCHES FROM THE
NORTHERN HIGH PLAINS EASTWARD, BUT DID INCLUDE A SMALL SLIGHT RISK
ACROSS PARTS OF CENTRAL MINNESOTA AND WISCONSIN ON THE DAY 5 ERO
GIVEN AMPLE MOISTURE, INSTABILITY, AND SOME SOIL SENSITIVITY. SOME
RAIN WILL CONTINUE EAST INTO THE OHIO VALLEY AND NORTHEAST MIDDLE
OF NEXT WEEK.
MONSOONAL MOISTURE ON THE WESTERN SIDE OF THE RIDGE SHOULD
CONTINUE A WET AND UNSETTLED PATTERN STRETCHING FROM THE FOUR
CORNERS REGION NORTHWARD INTO THE ROCKIES/HIGH PLAINS MOST OF THE
PERIOD. MARGINAL RISKS ON THE ERO CONTINUE ACROSS PARTS OF THE
SOUTHWEST/FOUR CORNERS SUNDAY AND MONDAY.
MUCH OF THE WEST COAST SHOULD BE MODESTLY ABOVE NORMAL MUCH OF THE
PERIOD, BUT THE GREATEST THREAT FOR HAZARDOUS HEAT WILL BE ACROSS
PARTS OF SOUTHERN CALIFORNIA AND THE DESERT SOUTHWEST THIS WEEKEND
INTO EARLY NEXT WEEK, WITH DAYTIME HIGHS EXCEEDING 110F LIKELY.
ABOVE NORMAL TEMPERATURES ACROSS THE CENTRAL U.S. SHOULD SLOWLY
SINK SOUTH AND EASTWARD WITH TIME. THIS EQUATES TO MODERATE TO
MAJOR HEATRISK ACROSS THE SOUTH-CENTRAL TO SOUTHEAST U.S.., WITH
SOME LOCALIZED EXTREME ACROSS PARTS OF THE CENTRAL GULF COAST
STATES. NORTHERN TIER SHOULD REMAIN NEAR TO BELOW NORMAL THROUGH
THE PERIOD AS WEAK SHORTWAVE ENERGIES MOVE THROUGH.
KONG/SANTORELLI
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC MEDIUM
RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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